Introduction to Computers
A beginners approach
Questions ?
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Computer is an ……………device.
A program is a sequence of ………………….
Raw facts and figures are called ………….
Processed data is called …………………
Keyboard is an …………… device.
RAM is ………………………………..
ROM is ………………………………..
Hard Disk is a ……………………………….
Computer
The
word
“compute”
computer
which
comes
means
to
from
the
calculate.
Initially computers are mainly used for
scientific calculations (research purposes).
Presently more than 80% of works done by
computers are data processing.
Computer is an electronic device that
comprises the following components
Monitor
(output)
Speaker
(output)
System unit
(processor, memory…)
Printer
(output)
Storage devices
(CD-RW, Floppy,
Hard disk, zip,…)
Scanner
(input)
Mouse
(input)
Keyboard
(input)
What does a Computer do ?
Computers can perform four general
operations, which comprise the information
processing cycle.
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Input
Process
Output
Storage
Data and Information
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All computer processing requires data, which is a
collection of raw facts, figures and symbols, such
as numbers, words, images, video and sound,
given to the computer during the input phase.
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Computers manipulate data to create information.
Information is data that is organized, meaningful,
and useful.
Why Is A Computer So Powerful?
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Speed:
A computer is a very fast device. It can perform
in a few seconds, the amount of work that a
human being can do in an entire year.
Accuracy:
The accuracy of a computer is consistently high,
and the degree of accuracy of a particular
computer depends upon its design. Error can
occur in a computer. However, these are mainly
due to human and incorrect data.
Why Is A Computer So Powerful?
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Diligence:
Unlike human beings, a computer is free from
monotony, tiredness and lack of concentration. It
can continuously work for hours, without creating
any errors.
Versatility:
A computer can perform a series of operations
concurrently. A computer is capable of
performing different types of tasks.
Why Is A Computer So Powerful?
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Power of Remembering:
A computer can store and recall any amount of
information because of its secondary storage capacity.
Every piece of information can be retained as long as
desired by the user, and can be recalled, as and when
required.
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No I.Q.:
A computer possesses no intelligence of its own. Its I.Q.
is zero, at least until today. Only the programmer/user
can determine what tasks a computer can perform.
Why Is A Computer So Powerful?
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No Feelings:
Computers are devoid of emotions. Computers
can not make judgements on their own, their
judgement is based on the instructions given to
them in the form of programs that are written by
programmers.
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Ability to communicate with other computers.
How Does a Computer Know
what to do?
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It must be given a detailed list of instructions,
called a compute program or software, that
tells it exactly what to do.
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The basic function performed by a
computer is the execution of a program.
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A program is a sequence of instructions,
which operates on data to perform certain
tasks.
What Are The Primary
Components Of A Computer ?
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Input devices.
Central Processing Unit
(containing the control
unit and the
arithmetic/logic unit).
Memory.
Output devices.
Storage devices.
Input Devices
 Keyboard.
 Mouse.
The Keyboard
The most commonly used input device is the
keyboard on which data is entered by manually
keying in or typing certain keys. A keyboard
typically has 101 or 105 keys.
The Mouse
Is a pointing device which is used to control the
movement of a mouse pointer on the screen to
make selections from the screen. A mouse has
one to five buttons. The bottom of the mouse is
flat and contains a mechanism that detects
movement of the mouse.
The Central processing Unit
The central processing unit (CPU) contains
electronic circuits that cause processing to
occur. The CPU interprets instructions to the
computer, performs the logical and arithmetic
processing operations, and causes the input
and output operations to occur. It is considered
the “brain” of the computer.
Memory
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Memory also called Random Access Memory or
RAM (temporary memory) is the main memory of
the computer. It consists of electronic components
that store data including numbers, letters of the
alphabet, graphics and sound. Any information
stored in RAM is lost when the computer is turned
off.
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Read Only Memory or ROM is memory that is
atttched on a chip that has start-up directions for
your computer. It is permanent memory.
Amount Of RAM In Computers
The amount of memory in computers is typically
measured in kilobytes or megabytes. One kilobyte (K
or KB) equals approximately 1,000 memory locations
and one megabyte (M or MB) equals approximately
one million locations A memory location, or byte,
usually stores one character.
Therefore, a computer with 8 MB of memory can store
approximately 8 million characters. One megabyte can
hold approximately 500 pages of text information.
Output Devices
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Output devices make the information
resulting from the processing available for
use. The two output devices more commonly
used are the printer and the computer
screen.
The printer produces a hard copy of your
output, and the computer screen produces a
soft copy of your output.
Categories Of Storage
• Magnetic
– Floppy disks
– Zip disks
– Hard drives
• Optical
– CD-ROM
– DVD
• Solid state storage devices
– USB Key (a very common form of solid state
storage)
Magnetic Storage
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Exploits duality of magnetism and
electricity
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Converts electrical signals into magnetic
charges
Captures magnetic charge on a storage
medium
Later regenerates electrical current from stored
magnetic charge
Polarity of magnetic charge represents bit
values zero and one
1. Magnetic Drives
Magnetic Disk
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Flat, circular platter with metallic coating that
is rotated beneath read/write heads
Random access device; read/write head can
be moved to any location on the platter
Hard disks and floppy disks
Cost performance leader for general-purpose
on-line secondary storage
1. Magnetic Drives: Storage Capacities
Floppy
~
disks
1 MB
Hard
drives
– 500 GB (TB is possible but very
rare)
~80
Floppy Disks
A floppy disk is a portable, inexpensive storage
medium that consists of a thin, circular, flexible
plastic disk with a magnetic coating enclosed in
a square-shaped plastic shell.
Hard Disks
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Another form of auxiliary storage is a hard disk. A
hard disk consists of one or more rigid metal plates
coated with a metal oxide material that allows data
to be magnetically recorded on the surface of the
platters.
The hard disk platters spin at a high rate of speed,
typically 5400 to 7200 revolutions per minute (RPM).
Storage capacites of hard disks for personal
computers range from 10 GB to 120 GB (one billion
bytes are called a gigabyte).
Compact Discs (CD)
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A compact disk (CD), also called an optical disc,
is a flat round, portable storage medium that is
usually 4.75 inch in diameter.
A CD-ROM (read only memory), is a compact
disc that used the same laser technology as
audio CDs for recording music. In addition it can
contain other types of data such as text,
graphics, and video.
The capacity of a CD-ROM is 650 MB of data.
DVD (Digital Video Disk)
DVD-ROM
– Over 4 GB storage (varies with
format)
– DVD- ROM (read only)
– Many recordable formats (e.g.,
DVD-R, DVD-RW; ..)
– Are more highly compact than
a CD.
– Special laser is needed to read
them
Blu-ray Technology
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Name
Derived from the blue-violet
laser used to read and write
data.
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Developed by the Blu-ray
Disc Association with more
than 180 members.
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Dell
Sony
LG
Blu-ray Technology Cont.
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Data capacity
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Because Blu-ray uses
a blue laser(405
nanometers) instead of
a red laser(650
nanometers) this
allows the data tracks
on the disc to be very
compact.
This allows for more
than twice as small pits
as on a DVD.
Answers
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Computer is an electronic device.
A program is a sequence of instructions.
Raw facts and figures are called data.
Processed data is called information.
Keyboard is an input device.
RAM is Random Access Memory.
ROM is Read Only Memory.
Hard Disk is a secondary storage device.
Thank You
Murugan R
Asst. Professor
Dept. of Computer Applications
MES College Marampally
Aluva – 683 107
www.LSP4YOU.COM
+919447177829
murugan@mesmarampally.org
mes.murugan@gmail.com